Reversing drum switch



3 Sheets-Sheet 1 98u/ I3?" /04 l m [v I v l. l. /l l.. M 8 6 w. G. DENNISQNA ETAL REvERsING DRUM SWITCH May 12, 1964 Filed Aug. 12, 1960 w. G. DENNlsoN ETAL 3,133,164

May 12, 1964 REVERSING DRUM SWITCH 3 Sheets-Sheet 2 Filed Aug. l2, 1960 mmvvom www f @www May 12, 1964 w. G. Dr-:NNlsoN ETAL 3,133,164

REvERsING DRUM SWITCH Filed Aug. l2, 1960 3 Sheets-Sheet 3 United States PatentOice 3,133,164 Patented May 12, 1964 3,133,164 REVERSING DRUM SWITCH Wiliiain G. Dennison and Clyde F. Robbins, Milwaukee,

and .lohn W. Vogel, Fon Point, Wis., assignors to (initier-Hammer, Inc., Miiwauiree, Wis., a corporation of Deiaware Filed Aug. 12, 196th, Ser. No. 49,224 12 Claims. (Cl. 20G-5) This invention relates to reversing drum switches and particularly to such a switch which is easily adjustable to change either the forward or reverse setting of the switch, or both, from a maintained position to a momentary one or different combinations thereof.

Reversing drum switches having adjustments for changing from a maintained position to a spring return action for either reverse or forward positions on both are not new. However, switches having this feature are either diiiicult to change, or making the change unduly stresses parts of the switch to the detriment of switch performance.

One object of this invention is to provide. an inexpensive reversing drum switch of improved construction in which a simple adjustment quickly, and without unduly stressing any part of the switch, converts a given setting of the switch actuating lever from a maintained setting to a momentary setting, or vice versa.

Another object is to reduce the time and effort required in assembling a reversing drum switch.

Still another object is to improve mechanical and electrical life in a switch of the reversing drum type.

The first object is accomplished by providing a cam follower assembly which may be snapped in a direction axial of the drum from engagement with one cam on the drum to another cam on the drum. The cams have a conventional configuration in which a maintained switch setting is obtained by providing a notch in the cam and a momentary setting is provided by contouring the cam to return the drum cylinder, which is biased toward the off position, to off when the rotative force exerted on the drum cylinder by the switch actuating lever is released.

The second object is accomplished by designing the drum and housing which supports the drum so that only a minimum number of parts are needed to construct the switch. The drum cylinder, its bearings, cams of selected varying designs, contact insulating discs and movable contact segment mountings are integrally molded as one piece. The drum housing in which the drum is mounted is comprised of a pair of molded blocks which when separated permit easy assembly of the drum cylinder and the stationary contacts. The molded housing blocks are secured together by a bolt at one end and at the other end are held during assembling by the cam follower-assembly which is mounted on the other end of the housing in operative engagement with one of the cams on the drum. Consolidating the several parts of the switch into a few integral moldings and reducing the number of fasteners obviously reduces assembly costs.

The third object is accomplished by preloading the stationary contact ngers which are mounted on the molded housing blocks. These fingers are flat before assembly in the block chute. One end of the contact finger is mounted on one surface of the block and the other end resiliently rests on another surface of the block which is spaced from the plane of the first surface so that the contact finger is flexed. This iexure reduces contact bounce when the switch is closed. This reduction of contact bounce substantially reduces arcing and hence contact wear. The initial contact pressure obtained by preloading the stationary contact fingers assures an accurate arc gap and prevents accidental distortion of the station- VFIG. 8) which is mounted in a housing comprised of a ary contact fingers. This also permits the use of a more flexible spring for the stationary contact fingers and there is thus less effect on iinal contact pressure from dimensional variations of associated parts.

Other objects and advantages will be pointed out in, or be apparent from the specification and claims, as will obvious modifications of the two embodiments shown in the drawings in which:

FIGURE 1 is a side sectional view of a switch of the present invention mounted on a flush plate and constructed for oil tight operation;

FIG. 2 is a side elevation of a modified switch mounted on a frame and including a partial sectional view of the handle mounting structure;

FIG. 3 is a top plan view of the switch of FIG. 2 with the switch cover broken away;

FIG. 4 is a front view of the switch taken on line 4--4 in FIG. 3;

FIG. 5 is a front view of the switch of FIG. 2 with the handle removed and portions of the indicator hub broken away to show the means for limiting handle rotation;

FIG. 6 is a .front view of an indexing plate showing the handle positioning ribs thereon;

FIG. 7 is a sectional view taken on line 7 7 of FIG. 2;

FIG. 8 is anelevational side view of a drum cylinder;

FIG. 9 is a back elevation of the switch housing;

FIG. l() is a sectional view taken on line 10-10 in FIG. l;

FIG. 11 is a sectional View of the cam taken on line lll-11 in FIG. 8;

FIG. 12 is a sectional View of the other dissimilar cam taken on line 12-12 in FIG. 8; and

FIG. 13 is a side sectional view of a modified and simplified handle and mounting structure therefor.

The modiiication shown in FIGS. 2 through 5 is similar to the switch of FIG. 1 except that it is mounted on a frame provided with a cover instead of on a flush plate as in FIG. l and certain oil tight features have been omitted. The parts in FIGS. 6 through 12 are common to both modifications. The simplied handle mounting structure is adapted for use in either of the aforementioned modifications if sealing is not required.

Referring to the drawings, broadly speaking, the present switch consists of a rotatable drum cylinder 10 (see pair of molded blocks 12 and 14 (FIG. 3) and a cam follower assembly 16 (FIG. 2) which includes arms that snap into engagement with the housing blocks at one end and bear on cams molded into the drum cylinder at the other end. The cam follower assembly bothholds the housing blocks together and biases the drum to a position in which the movable contacts carried by the drum assume an open position with respect to the stationary contacts mounted on the housing blocks. The cam follower assembly may be shifted to bear on a selected cam. This shiftable feature permits a single switch to be used for both momentary on and maintained on settings in both the forward and reverse positions of the switch. Various combinations of these settings are obtained according to the design of the particular cam with which the cam follower assembly is engaged.

The housing blocks are identical except that one is a right hand block and the other is a left hand block. Therefore, only one block will be described in detail. Each housing block is an integral molding and has sepa- `ratechambers or pockets separated by divider walls 18 y(FIG. 1).

Each divider wall includes a semi-circular groove 20 therein which, when the left and right hand blocks are assembled, forms acircular groove inside the housing which receives an arc barrier 22 molded into the rotatable drum. At the top of the housing block there is a depression 24 (FIG. 7) running longitudinally in the molding and this both provides room to connect the terminal fingers to the housing and also gives clearance for insertion of a screwdriver to tighten a screw which is inserted through a hole 26 in the housing wall at the rear end of the depression to connect a similar housing in tandem with the one described. The chambers inside the block open to the block exterior through windows 23 (FIGS. 2 and 7) in which terminal fingers 30 are mounted. The arc gases formed inside the housing upon opening the switch are dissipated through this window and they pass by the terminal fingers which exert a cooling eifect thereon. The block exterior is molded to provide a separate stall or chute 32 (FIG. 3) for each terminal finger for purposes of insulating adjacent terminals. The terminals are secured to the block at the top 34 by means of a rivet or screw 36 which extends through the wall portion 38 between the depression molded in the top of the block and the terminal stall molded in the block exterior as shown in FIG. 7. A flat mounting surface extends into each terminal stall both at the top and bottom of the stall and the bottom surface 40 (FIG. 7) is offset outwardly with respect to the top surface 42. Each terminal finger 30 is a flat metal strip which is long enough to bridge the top and bottom surfaces. When the terminal nger is rigidly secured to the block onto the top surface 42, the bottom end of the terminal finger, which carries a stationary contact 44, rests on and is biased against the offset bottom surface and thereby the terminal finger is pre-flexed. A rail 46 is molded into the block to overlie the terminal fingers thereby shielding the terminals against objects that would foul the terminals such as wire leads, etc. Pre-flexing the terminal fingers as described substantially reduces contact bounce and, therefore, arcing is reduced. The housing block below the Windows immediately adjacent the stationary contacts tends to burn, and so an opening 43 (FIG. 2) is cut in the block to remove this portion of the housing and this opening also provides a port for the arc gases. The rear end of each block has a semi-circular opening 50 (FIG. 9) therein to journal a circular bearing member 52 molded into the drum cylinder. Openings 54 (FIG. l) are molded in the front end of each block and cooperate to permit the front of the drum cylinder to pass to the exterior of the housing upon assembly of the housing with the drum cylinder therein. At the front end of each housing block, the integral cam follower support member 56 (FIG. 2) extends forwardly and has a groove 58 (FIG. 4) in the side which runs parallel with the rotational axis of a drum cylinder mounted in a complete housing. This groove has three wedge shaped depressions 60 (FIG. 3) molded in the bottom which serve to receive and hold a cam follower arm in a selected position as described below. Support member 56 of each block also has half of a nut and bolt depression 62 (FIG. 3) molded therein which cooperates with the other housing member to form a complete chamber for receiving a nut 64 and bolt 66 for rigidly securing the housing to a mounting frame 68. A fastener projection 70 (FIG. 2) also extends from the front end of each housing block and has a bolt hole and nut holding cavity 72 therein. These projections also serve to connect the housing to the mounting frame. At the rear end of the block there is a transverse hole 74 (FIG. 9) in each block which lines up with an identical hole in the other block and receives a bolt 76 which holds the two housing blocks together at the rear. The blocks are temporarily held together at the front by a cam follower assembly while the switch is being assembled which will be described below.

The drum cylinder is integrally molded and designed for cooperation with the housing. The drum cylinder has a circular end 52 (FIG. 8) at the rear which is journaled in the circular opening 50 in the rear of the housing. This circular end has a cross shaped depression 78 (FIG. 9) therein adapted for connection to the front end of another similar drumcylinder. A pair of circular discs or arc barriers 22 project transversely from the longitudinal axis of the drum cylinder and have peripheries which fit into circular grooves formed in the housing. These discs serve to divide the inside of the switch housing into three separated chambers in which the contacts are located. The front S2 of the drum cylinder projects outside the housing through the opening therein and has a pair of integrally molded cams 84, 86 (FIG. 4) spaced along the axis of the drum. These cams are dissimilar, as seen clearly by comparing FIGS. l1 and l2, so that different combinations of momentary on and maintained on switch settings may be obtained according to which cam is engaged by the cam follower which controls the switch drum.

The drum cylinder has grooves 8S (FIG. 8) into which movable contacts 9i?, having slots 91 (FIG. 10) complementary with the shaft grooves, tit and these contacts are secured in place by a screw 92 which threads into the drum cylinder with its head overlying the contact to clamp it in place. Thus the contacts can be easily removed and replaced. The front end of the drum cylinder bears on the inside of a cylindrical opening in indicator hub 9S. The front end of the drum cylinder has four wedge shaped projections (FIGS. 4 and 8) and a flat side which project into register with complementary depressions and a flat side in indicator hub 98. The indicator hub has a boss 102 (FIG. l) which projects inside sleeve 104 which is secured to the flush plate or frame hereinafter described. These four wedge portions are sized to also fit into the cross shaped opening 73 in the rear end S2 of the drum cylinder so that several drums can be connected in tandem if desired. The indicator hub has a point 1116 (FIG. 5) which cooperates with indicia on the frame to show the switch position. A handle 107 is assembled against au indexing plate 108 which fits against the face of indicator hub 9S. The face 110 of the indicator hub has four radially extending ribs 112 (FIG. 5) which are sized to t in selected mating depressions 114 in the face of plate 108 (see FIG. 6). Plate 108 has sixteen of these depressions spaced in 22.5 degree increments so that the handle itself may be oriented as desired and will then be held in that position when the switch is finally assembled by tightening a screw 116 which extends through the handle, plate 108, and the indicator hub and into the end of the drum cylinder to clamp them together. T o prevent the handle from rotating relative to indexing plate 108, the latter is provided with a pair of radial projections which t into complementary depressions 117 in handle 107.

The indicator hub has abutments 111 thereon which cooperate with the shoulders 113 projecting from frame bearing sleeve 104 to limit the rotation of the indicator hub and drum cylinder. Providing these limit stops between the indicator hub and bearing sleeve prevents transmission of torsional shearing forces to the drum which would occur if the stops were provided directly between the drum and some other member.

Switch operation is controlled by ia cam follower assembly which consists of -a pair of arms 11.9 interconnected by a spring 11S` (FIG. 4). The arms each have a pair of spaced prongs 121V (FIG. 3) at Vtheir top end which fit in the wedge-shaped depression 60 in the groove 58 in support member S6. The lower end of each arm has a cam follower roller 1212 connected thereto. rl`he width and positioning of the housing cam follower support members 56 and the diameter of the drum cams 84 and 86 are such that the cam follower prongs snap into the depressions in the grooves and are biased by the interconnecting spring into squeezing engagement with a cam. There are three Wedge shaped depressions 6G in each groove 58 in member 56 and, if it is desired to engage the cam follower rollers with the front cam 86, the two spaced prongs oneach arm are snapped into the front and g providing middle depressions. If switch operation by the back cam 84 is desired, the prongs are snapped into the middle and rear depressions.

The cam follower arms 119 may be snapped axially from one position to the other by the application of force toward lthe desired direction of movement. In FIGS. 2 and 3, arms 119 are shown in the forward kposition closest to the handle end of the switch. Arms 119 are held in position by the engagement of prongs 120 with the middle and front depression 60. The arms 119 in their rearward position are illustrated in dotted lines in FIGS. 2 and 3. In the rearward position, prongs 120 engage the middle and rearward of depressions 60. The shifting of arms 1119 between forward yand rearward positions may be accomplished manu-ally. Upon the application of sufficient force, prongs 120 ride up the sloping surfaces and out of depressions 60 `because of the elasticity of spring 1'18 and the sloping surfaces of depressions 60. The prongs 120 then move until they become alined with and snap into the depressions 60 which provide for the opposite position of arms `119.

The cam follower assem-bly squeezes the cam it engages and all of the various cams employed have depressions 123 (FIGS. l1 and 12) into which this squeezing action normally biases each cam roller so that the drum is in off position. When the switch is actuated by rotating the handle it is sometimes desired to have the switch turned off immediately upon handle release and in other applications it is desired that the switch positions be maintained. The rear cam 84 has cam surfaces 121 which return the drum from FWD to off position when the handle is released. Cam 84 also has notches 124 which maintain the cam in REV position when the handle is rotated to the opposite extreme. The front cam 8-6 is similar to cam 84 except surfaces 121 and 124 are interchanged so that shifting the cam follower to cam 86 changes a spring-return from FW setting to a spring return from REV and changes maintained REV to a maintained FWD setting. Of course, one cam can have two momentary or two indexed contours thereon to provide different combinations. The other cam would then have a different configuration to provide other desired settings. These cam contours are conventional and the novelty lies in the shiftable construction of the cam follower assembly which permits two dierent combinations of momentary on and maintained position settings to be obtained from the same switch merely by snapping the follower assembly from one position to another. Various cam combinations can Ibe provided by providing various designs of cylinders.

Oil tight cavity mounting of the switch is possible by a disc-shaped-washer-mounting-groove 126 ",(FIG. l) around the bolt hole in the face of the indicator hub and `by also providing a circular washer groove 128 in the surface of boss 102 which is journaled in sleeve 104. Neoprene washers 130, 132 or the like are mounted in these grooves and the ush plate 134 (used in lieu of the frame described above) to which the housing is bol-ted is sealed to the wall 136 of the cavity in which the switch is being mounted ywith a gasket 138 thereby providing an oil tight switch. The annular flange of sleeve 104 which rests against flush plate 134 is provided on the surface facing plate 134 with a circular groove for accommodating and compressing therebetween a resilient sealing member 140 of the O-ring type to seal sleeve 104 to plate 1l34. Referring to FIG. 13, there is shown a simplified operating handle and mounting structure therefor. Handle 142 is constructed as. if indexing plate 108 in FIG. 2 were made integral with handle 107. Thus, handle 142 in FIG. 13 is provided with radial depressions 4144 similar to depressions 114 in plate 108 shown in FIG. 6 to afford selective orientation of the handle relative to indicator hub `98, the latter being similar to the like referenced hub in FIG. 2. Otherwise, the structure in FIG. 13 is similar to that in FIG. 2.

`Although several modifications of the present invention 6 have been illustrated and described, it will be apparent that various changes and modifications may be made therein without departing from the scope of the appended claims.

We claim:

1. In a reversing drum switch, a rotory drum cylinder having a contact mounted thereon, a plurality of stationary contacts disposed around the periphery of said drum cylinder to make contact with said drum cylinder contact as said drum is rotated, a plurality of cams of different contours on said drum cylinder, Iand cam follower means shiftable along the rotational axis thereof and including means for selective engagement 'with said cams -to provide different position indexing and biasing modes for said drum cylinder.

2. The combination laccording to claim l in which said cams are integrally molded with said drum cylinder.

3. The combination according to claim 1, together with a housing `forming a support for said drum cylinder and having a guide for said earn follower means to guide said means as shifted.

4. The combination according to claim l, in which one of said cams has a cam surface provided with a contour whereby the pressure of said cam follower against said contoured cam surface biases and maintains said drum cylinder in an on position.

I5. The combination according to claim l, in which one of said cams has a cam surface provided with a contour whereby the pressure of said cam follower against said contoured cam surface causes return of said drum cylinder to an off position when said rotating force is removed.

6. The combination according to claim 1, in which one of said cams has `a cam surface provided with a contour whereby the pressure of said cam follower against said contoured cam surface maintains said drum cylinder in on position and also returns said drum cylinder to off position when said drum cylinder is rotated in the other direction and released.

7. In a reversing drum switch, van insulative housing including means for rotatably mounting a drum cylinder, a drum cylinder rotatably mounted on said housing, a movable Contact mounted on said drum cylinder, a pair of stationary contacts mounted on said housing and spaced around the periphery of said drum cylinder in position to make electrical Contact with said movable contact upon rotation of said drum cylinder, a plurality of cams spaced along the rotational axis of said duum cylinder, each of said earns having radially positioned carnming surfaces, a pair of cam follower arm-s having ends engaging said housing and ends bearing on said camming surfaces of one of said cams, `and biasing means urging said arms to exert a squeezing force on said camming surfaces, means on said arms and complementary means on said housing for retaining said ends engaging said housing in any one of a plurality of positions whereby said arms lare shiftable along said rotational axis to selectively engage any one of said cams.

8. The invention according to claim 7 in which said housing is made in two parts and said cam follower arms separately engage said parts to hold one end of said housing assembled.

9. In a reversing drum switch, a pair of right and lef-t hand housing blocks forming a housing, a drum cylinder mounted partially inside said housing and journaled thereon, said drum cylinder including at least two dissimilar cams projecting outside said housing and being spaced along the rotational axis of said drum cylinder, each of said housing blocks having a portion projecting alongside said cams and having a groove therein, said grooves extending generally parallel with the rotational axis of said drum cylinder, a pair of cam follower arms each engaging one of said grooves at one end and carrying a roller at the other end for engaging one of said cams, a spring interconnecting said arms whereby said arms are urged into said grooves thereby holding said housing blocks together and biasing said rollers into squeezing engagement with one of said cams, said arms being shittable in said grooves to engage the desired cam.

10. The combination according to claim 9 in which said drum cylinder has a movable contact thereon, said housing having stationary contacts mounted thereon for engagement with said movable contact when said drum cylinder is rotated, and means for preexing said stationary contacts whereby contact bounce is substantially reduced when said movable contact moves into engagement with said stationary contact.

11. The combination according to claim 9 in which said drum cylinder has a groove therein, a movable contact adapted to tit in said groove, and ya headed screw positioned to screw into said drnm cylinder so that its head overlies said contact and clamps said contact in said groove.

12. In a reversing drum switch, an insulating housing, a duim cylinder mounted for rotation in said housing, movable contacts mounted on said cylinder for rotation therewith, stationary contacts mounted in said housing for engagement by lsaid movable contacts when said cylinder is rotated in reverse directions, each said stationary contact comprising an elongated flat resilient spring having a contact tip secured intermediate the ends thereof for engagement lby certain of said movable contacts, and means effective when a movable Contact engages a stationary contact for providing initial contact pressure therebetween -comprising a planar mounting surface on said housing for each stationary Contact spring, means rigidly securing one end of said contact spring to said planar surface, and a portion on said housing otiset outwardly from the plane of said surface for restraining the other end of said contact spring to cause said contact spring to be prestressed when the first mentioned end thereof is rigidly secured.

References Cited in the tile of this patent UNITED STATES PATENTS 2,590,658 Silvius Mar. 25, 1952 2,761,655 Lunden et al. Sept. 4, 1956 2,848,569 Moss et al. Aug. 19, 1958 2,905,788 Harrison Sept. 22, 1959 20 2,933,568 Harada Apr. 19, 1960 FOREIGN PATENTS 510,925 Italy Jan. 24, 1955 

1. IN A REVERSING DRUM SWITCH, A ROTORY DRUM CYLINDER HAVING A CONTACT MOUNTED THEREON, A PLURALITY OF STATIONARY CONTACTS DISPOSED AROUND THE PERIPHERY OF SAID DRUM CYLINDER TO MAKE CONTACT WITH SAID DRUM CYLINDER CONTACT AS SAID DRUM IS ROTATED, A PLURALITY OF CAMS OF DIFFERENT CONTOURS ON SAID DRUM CYLINDER, AND CAM FOLLOWER MEANS SHIFTABLE ALONG THE ROTATIONAL AXIS THEREOF AND INCLUDING MEANS FOR SELECTIVE ENGAGEMENT WITH SAID CAMS TO PROVIDE DIFFERENT POSITION INDEXING AND BIASING MODES FOR SAID DRUM CYLINDER. 